Information Type

What is an investigational drug?

An investigational drug is one that is under study and is not approved by the U.S. Food and Drug Administration (FDA) for sale in the United States. Medical research studies are conducted to evaluate the safety and effectiveness of an investigational drug. These research studies are also called clinical trials. Once an investigational drug has been proven safe and effective in clinical trials, FDA may approve the drug for sale in the United States.

What is rintatolimod?

Rintatolimod is an investigational drug that is categorized as a biological response modifier.2 Biological response modifiers (also called immunomodulators) are substances that help to activate, boost, or restore normal immune function.3,4

Rintatolimod was studied for its ability to delay re-emergence of HIV during structured treatment interruptions of antiretroviral therapy (ART). A structured treatment interruption is a planned break from treatment, for example, ART. Structured interruption of ART is not recommended outside of controlled clinical trials.5,6

Rintatolimod was also studied as a medicine to add to ART in people whose current HIV medicines weren’t controlling their HIV infection.7 Also, rintatolimod has been studied for various non-HIV-related uses, including to treat chronic fatigue syndrome and cancer and to boost the body’s immune response to a flu vaccine.8-11

How are clinical trials of investigational drugs conducted?

Clinical trials are conducted in phases. Each phase has a different purpose and helps researchers answer different questions.12

Phase I trials: Researchers test an investigational drug in a small group of people (20–80) for the first time. The purpose is to evaluate its safety and identify side effects.

Phase II trials: The investigational drug is administered to a larger group of people (100–300) to determine its effectiveness and to further evaluate its safety.

Phase III trials: The investigational drug is administered to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or equivalent treatments, and collect information that will allow the investigational drug to be used safely.12

In most cases, an investigational drug must be proven safe and effective in a Phase III clinical trial to be considered for approval by FDA for sale in the United States. Some drugs go through FDA’s accelerated approval process and are approved before a Phase III clinical trial is complete. After a drug is approved by FDA and made available to the public, researchers track its safety in Phase IV trials to seek more information about the drug’s risks, benefits, and optimal use.12

In what phase of testing is rintatolimod?

Rintatolimod for HIV treatment has been studied in Phase II clinical trials.2

What have recent studies shown about rintatolimod?

A Phase II study looked at whether rintatolimod could extend the time a person could stay off HIV medicines during structured interruptions of ART before their HIV began to rebound. (A rebound is when there are detectable levels of HIV in the blood after a period of undetectable levels.) During this study, up to three structured interruptions of ART were planned over a 64-week period. All participants in this study had taken HIV medicines before entering the study (treatment-experienced) and had a viral load level (the amount of HIV in the blood) of less than 50 copies/mL while on ART. The participants were divided into two groups. One group received rintatolimod by intravenous injection twice weekly during the structured interruptions of ART. In the other group (the control group), the participants did not receive rintatolimod during the structured interruptions of ART. The structured interruptions of ART were stopped once a participant’s viral load rose to certain detectable levels.5,6

In this study, participants receiving rintatolimod were able to stay off HIV medicines for longer (while maintaining controlled viral load levels) during the initial structured interruption of ART than participants in the control group. The average duration of the first structured treatment interruption in participants receiving rintatolimod was 27 weeks, whereas it was 13 weeks for participants in the control group. CD8 T lymphocytes (a type of immune cell that recognizes and destroys cells infected with microorganisms, such as bacteria or virus) increased more in participants receiving rintatolimod than in participants in the control group. In terms of safety, side effects with use of rintatolimod were described as being generally mild.6

Rintatolimod was also studied in a Phase II trial as a medicine to add to ART in people whose HIV medicines weren’t controlling their HIV infection. This study, however, was stopped prior to completion.7

What side effects might rintatolimod cause?

In the Phase II study looking at the use of rintatolimod during structured interruptions of ART, side effects were generally mild and cleared up without treatment.6

Because rintatolimod is still being studied, information on possible side effects of the drug is not complete. As testing of rintatolimod continues, additional information on possible side effects will be gathered.

Where can I get more information about clinical trials studying rintatolimod?

More information about rintatolimod-related research studies is available from the AIDSinfo database of ClinicalTrials.gov study summaries. Click on the title of any trial in the list to see the ClinicalTrials.gov trial summary and more information about the study.

I am interested in participating in a clinical trial of rintatolimod. How can I find more information about participating in a clinical trial?

Participating in a clinical trial can provide benefits. For example, a volunteer participant can benefit from new research treatments before they are widely available. Participants also receive regular and careful medical attention from a research team that includes doctors and other health professionals. However, clinical trials may also involve risks of varying degrees, such as unpleasant, serious, or even life-threatening side effects from the treatment being studied.12